Liquid propellant cartridge



53 [FIG-2 l T13 C. F. TURNER LIQUID PROPELLANT CARTRIDGE Filed Nov. 28, 1962 Kg, 5 53 la 39 Il" 7 f 32 6 l I4 1 '00 'y' FIG v "om,

1 g k x "j 117 /4/ h ENTOR CHARLES TUR/VER A TTOR/VE V United States Patent O 3,162,123 LlQUlD ERPELLAN'E CRTREDGE Charles l?. Turner, itl/leunt Carmel, Conn., assignorto @lin Mathieson Chemical Corporation, a corporation of Virginia l Y Filed Nov. 28, 1962, Ser. No. 240,521 S Claims. (Cl. to2-3% This application relateslto an explosive device for generating propellent gas andparticularly to a cartridge containing a liquid propellant useful in generating a gaseous propellent product for a short duration suitable for power- Y ing various apparatus, such as for driving projectiles from a gun or fasteners from an explosive actuated fastenerk driving tool.

For ignition of the herefore well known solid propellants, such as those of the smokeless powder type, a relatively complex type of primer, usually percussive or electrical, is required. Although the rapidly expanding mass of hot gas is produced in this way conveniently from a primed powder unit or cartridge, the primers which are relatively expensive precision items add considerably to the cost of the whole unit or cartridge and undesirable side effects of the primer and/or solid explosives and the cartridge assembly itself make such cartridges not entirely suitable for certain uses. The powder may not be properly ignited or may fail toburn completely leaving' a dangerous residue, or the gaseous mass maybe undesirably contaminated with unburned particulate :material and also with cartridge fragments and with corrosive or other by-products not tolerable in the firing apparatus.

Furthermore, some priming devices suffer from the dissure at a desired pressure level, all'without the presence of a conventional and/or protruding exposed primer.

One object of this invention is to provide an economical cartridge of relatively simple but highly effective construction obviating the need for numerous components including a separate primer unit.v

Another object is to provide a cartridge free from an exposed primer structure susceptible to accidental discharge. l

Another object is to provide a cleanburning cartridge structure adapted for percussive auto-ignition and corn plete combustion of the propellent charge without introducing extraneous elements. j

Another object is provision of a cartridge with built-in sealing means effective not only with respect to the contents prior to lrng but also with respect to the driving apparatus during tiring.

Still another object is to provide a high pressure gas generating cartridge containing a liquid propellantA of the mixed alkyl nitrate type charged in a way especially suited for driving a fastener and/ or the ram of a power hammer.

Other objects and advantages will be evident from the following description and accompanying drawing kwherein FIG. 1 is a view in longitudinal cross'section showing a fastener driving tool with a typical projectile fastener and including a liquid propellent cartridge for actuation,`

all in accordance with this invention; n

FIG. 2 is an enlarged elevational View of the cartridge of FIGURE 1 shown in longitudinal cross section;

FIG. 3 is an enlarged fragmentary view in'cross section showing part of another embodiment of cartridge'otherj Y attain Patented Dec. 22, i964 Cce wise similar to that of FGURE 2 but modified at one end; and

FIG. 4 is an enlarged'fragmentary view showing in cross section the blown `end part of the cartridge of FIGURE 2 mounted in a tool'only part of whichfis shownwith the cartridge `adjacent another type -of orice plate' for-which the cartridge is especially adapted. Y

In accordance' with this invention there is provided a cartridge l including a case 10, a closure 11, and adhesive f layer i2, both mounted in a predetermined position with yieldable iixation with respect to each other andthe case to form with the case acavity 13, a liquid propellant 14 occupying part of the cartridge cavity hermetically sealed by the closure and its layer, and a body of gas l5 loccupying the rest or" the cavity. The gas,`the case, and the closure coact for adiabatically igniting the propellant by a percussive ring means.` The case is of a relatively hard ,elastic metal such as 70:30 brass.

vThe bore preferably has cylindrical inside walls of substantially uniform diameter but may converge slightly by a few thousandths of an inch the better to seal with closure lill `and its sealing layer l2. To give desired strength f and ease of extraction the case thickness in a 0.22 caliber becomes thickened to about 0.010 of an inch adjacent rim 18. 'The closure takes the form of a cup-likepiston ll which has skirt 19 and is made of relatively softmetal Y such `as copper or a highrcopper alloy containingabout sive'layer of suitable plastic `and sealing material 121, preferably an epoxy resin.

The piston and layer may be integrated as one piece of'any suitable resin such as epoxy resin, polyethylene,

polypropylene, or the like compatible with the propellant v and case. Y This `arrangement is sealing, not only during storage prior to use but also during firing.

Rim 18 preferably hasa hollow in communication withv and longitudinally upon firing.

the cavityiand for sealing is expandable both transversely At'the` other end formed integrally with the case, the

cartridge has a thickened closed end 17 and an outwardly extending 'rim structure 1S all around the cartridge'beven its bore 16 and the thickened end 17 forming a u ge. v

With due regard to proportionality with'respect to caliber, for the cartridge of FIGURE 2 rupturable end 17 is further thickened from about 0.015 to about 0.025of an inch from rim to rim for a .22 caliber shell.

As will appear hereinafter from further description, `this end structure is not rupturable until more than a predetermined pressure needed for ignition is reached and provides a desirable sealing arrangement for the dispensing end of the cartridge as well as providing an advantageous means for operatively dispensing. the high pressure gas generated. i

The liquid propellant le with which the cartridge is charged in all embodiments is a monopropellan-t base or a mixture producing substantially no ashupon'burning and is susceptible to ignition by adiabatic compression 50 mole percent, and 60 mole percent ethyl nitrate in` Specifically, a 60-40 mixture, having a boiling range of from to 231 F. :and a` normal propyl nitrate.

freezing point, at standard conditions of temperature and pressure, below l48 F., made up of 60 percent-.ethyl nitrate and 40 percent n-propyl nitrateV was found to have the desired sensitivity and reliability from the standpoint of capability of adiabatic ignition and stability.

For the best operative range of adiabatic percussive ignition in contradistinction .to electric ignition, the cartridge is loaded with propellant to the extent from about percent to about 70 percent of the volumetric capacity of the cartridge cavity. ln this range of loading, for eX- arnple, a small arms caliber case such as a .22 caliber case having a length of slightly less than about one inch and a volumetric capacity of about 0.57 cc. when capped by `the recessed piston closure 11 as shown in FIGURE 2 was found suitable for most driving applications. ln this caliber range of cartridge for 1t-inch diameter fasteners, a liquid charge of about 0.08 cc. to about 0.24 cc. is contemplated for driving projectile type of fasteners in the range from low power applications -to high power applications, respectively. This represents a liquid propellant loading to the extent of from about 15 percent to about 45 percent of the volume of the cartridge cavity.

Easiest and still safe adiabatic ignition by percussion occurs in the loading range of from about 15 percent to about 45 percent. Either the cartridge caliber or cartridge length, preferably the latter to allow use of one caliber of tool, may be selected so that the liquid charge loaded at substantially atmospheric pressure, or a bit more, frorn the insertion of the piston 11, together with the igniting body 15 of any suitable gas such as plain air, is in this loading density range for each of a series of cartridges ranging from the lcw power cartridges to the high power cartridges. Alternatively, the length of all the cartridges of a series of given caliber may be fixed and instead the position of the cup-shaped piston closure 11 may be varied to suit the liquid charge so that the extent of insertion into the bore 16 varies inversely with the amount of propellant 12.

Propellant loading at high density around 6'5-45 percent of the volumetric capacity has the advantage not only of a short cartridge but also of a short ignition stroke, useful for devices having a biased tiring mechanisrn independent of a manual blow as from a hand hammer.

One suitable device for discharging a typical cartridge is the tool of FIGURE 1 consisting of a breech body 2, a barrel section 3 with a barrel breech piece 4, and a drive plunger 23 having a hand hammer striking head 24 at one protruding end', a retaining lange 25, and igniter bolt 26 sized to tit into the cartridge bore with slight clearance. The body carries the cartridge rim-end-forward in a chamber 31 and is adapted by any suitable articulating coupler such as the male thread end 33 to carry the barrel section 3 in a way allowing for cartridge loading and extraction. The tool, between this section and the body, has in axial alignment with the cartridge chamber, a counterbore 34 forming a relief sealing area for slideably receiving the rim l of the drive cartridge in this area adjacent the breech 4 in the form of a replaceable oriiced plate forming one end of the chamber. In axial alignment body 2 also has the bore 37 for slidably receiving and guiding plunger 23 and has further enlarged bore 3S for receiving the retaining flange. Either of these bores may carry a suitable return mechanism such as the spring 27 which facilitates acceptance of the cartridge during loading. The retainer cap 2S threadedly carried on the rear end of the body is perforated at 3@ for passage of the shank Z9 of the plunger slidably.

The barrel section bore 39 receives the tool piston 5 in sliding relation with the enlarged piston head 51 providing a shoulder 52 operative with the ball check Sil to retain the piston in the ready-to-lire position as shown in the drawing. The piston at its threaded front end 53 is adapted to carry a fastener 6 of the projectile type to be driven into the target body 1&9.

ln operation, when striking head is hit by a han mer, or when the plunger is otherwise subject to an iml pact thrust, the flat ended bolt or rod 26 pushes the cartridge closure piston 11 inwardly to ignite the propellant in accordance with this invention.

For the cartridge of FGURE 2, the breech of the tool is provided as an orificed plate 4 having a central cartridge perforating and jet forming orice 41 mounted threadedly in the tool between the cartridge chamber 31 and the barrel bore 39.

For this cartridge the breech may advantageously take the form of the inultiperforated plate 42 shown in FlG- URE 4, also detachably mounted in barrel section 3 and having a circumferentially spaced array of smaller ori- 'ioes 43 underlying the cartridge rim 1S at least in part. This peripheral array in overlapping relationship with rim 13 coacts with Ithe rim structure and. orifices to produce not only the explosive metal deformation 18A of the rim into counterbore 34 for'cre'ationv of the substantially complete seal peripherally but also to produce' the plurality of improved perforations 20 and their retained rlaps 21 swung asi'd'e by the jet and rim coaction wit-hout severance and least affected by erosion from the explosive Jets.

In breech orice 41 (FIGURE 1)' the entry isr advantageously counterbored and then is chamfered on the counterbore edge to give an annular recess at the entry for better perforation beginning'at the center an'd fo'rmation of an annular orifice lip extruded and layed back therein out of the way of the emerging jet to avoid blowing out a disc of metal. p

With breech piecesV having' an enlarged and/or plain straight opening, the cartridge is `best rnoidilied according to FIGURE 3 wherein the cartridge 101 has a thickened end 117, and rim 118 at one end of case 11)V as in the previous embodiment but with the diiference 'that the center of 117 is gradually thinned 'to the center to adapt it for rupture beginning at' the center and frmation of an extruded orifice lip, occurring at the thinned area 141 without throwing any big metal fragment into the. apparatus.

The skirted piston closure 11 is set into the cartridge cavity deep enough to form a recess at least deep enough for reception therein of the thin layer 12 of plastic sealant and adhesive against whichV the type of rod 26 strikes, thereby rupturing the adherence to case 1t)f while form"- ing a still better seal of the compressed layer as the closure 11 is put into movement to compress the gaseous body 15 adiabatically and spring skirt 19 outwardly into greater snugness as the closure advances until ignition occurs.

Thereupon, end 17 is ruptured to form an orifice or orices o-f an area of perforation corresponding to a diameter of slightly less than about s of an inch, i.e. 0.122 to 0.124 of an inch found to be suitable in a .22 caliber shell to develop penetration velocities from about 300 to 550A feet per second with a projectible fastener and piston assembly weighing around 25 to 35 grams.

Layer 12 is preferably an epoxy resin ofthe type made by reacting bisphenol and epichlorohydrin' and having a reactive epoxy group suitably4 modified to have the rare combination of tougheners, flexibility, chemical resistance, water penetration resistance', and high adhesion to metal. Such adhesives are made by Shell ChemicalV Corporation and one suitable example is Epoxy-Resin Laboratory Paint available from Fisher Scientific under the designation #13-313-10113.

Transversely and in length the cartridge for e'ach caliber is proportioned to receive an adequate quantity of propellant while leaving adequate space for the ignition gas and for the compression stroke needed to adiabatically rire the cartridge. The fired cartridge is extracted by separating the breech body 2 and barrel sectionv 3 at'threads 33 and then tapping head 24' until rod 26 thrusts the opened case out of chamber 31.

What is claimed is:

1. A cartridge for generating propellent gas at high pressure comprising a tubular case having a generally cylindrical mouth at one end of its length and a closed end wall at the opposite end, said end wall having a thickness such that rupture occurs at a predetermined pressure to provide a propellent gas dispensing opening in said case, a charge of propellant adapted for percussive adiabatic compression ignition disposed in said case, a piston completely received snugly within said case adjacent the mouth, a superposed layer of plastic resin in sealing and adhesive relationship with said piston and case within the mouth to define with said case a compression cavity containing said charge, sai-d piston being frictionally retained by said case and adhesively retained b-y said layer against movement out of said case to thereby seal said charge under substantially atmospheric pressure, said piston having an inner concave surface to form a gas sealing skirt in said cavity and an outer surface protectively exposed in said case under said layer operative to receive a blow through said layer to compress said y layer and drive said layer and piston inwardly against said charge whereby said charge is compressed above atmospheric pressure until said propellant is ignited adiabatically and said end wall subsequently ruptured at said high pressure.

2. The cartridge of claim 1 wherein the layer is an epoxy resin.

3. The cartridge of claim 1 wherein the propellant is a 60:40 mixture of about 60 mole percent ethyl nitrate in normal propyl nitrate and occupies from about percent to about 70 percent of the cavity volume enclosed by said case and piston.

4. The cartridge of claim 3 wherein the propellant 0ccupies from about 15 to about 45 percent of the volume of said cartridge.

5. The cartridge of claim 4 wherein the propellant oc- ,5

cupies from about 45 to about 65 percent of the volume of said cartridge.

6. The cartridge of claim 1 wherein the end wall is thick relative to said case and is centrally thinned to deline the rupturable area.

7. The cartridge of claim 1 wherein the end wall is centrally thinned gradually toy define the rupturable area.

8. A high pressure propellant gas generating cartridge including an elongated tubular sidewall, an integral closure at one end of said sidewall and an open mouth at the other end, said integral closure having a thickness generally greater than the thickness of said sidewall operative to rupture at a predetermined high pressure to provide a gas dispensing opening in said cartridge, a liquid propellant in said cartridge occupying a portion of the volume of said cartridge, air and propellant vapor occupying the remainder of the volume in said cartridge, a cup shaped member positioned inside the open mouth of said cartridge closing said open mouth at substantially atmospheric pressure, means overlying and adhesively positioning said member in place and sealing said open mouth, said means and said member being operative to move inwardly toward said propellant and compress said propellant to ignition when an external pressure is applied to said means and member to fire said cartridge.

References Cited by the Examiner UNITED STATES PATENTS 2,920,563` l/ De Caro 102-38 2,984,836 5/61 Schenkel 1--44.5v 3,007,409 11/61 Broske 102--38 3,048,849 8/62 De Caro 1-44.5 3,097,602 7/63 Turner 102-39 3,120,808 2/ 64 Gawlick et al. 102-44 SAMUEL FEDIBERG, Primary Examiner.

GRANVILLE Y. CUSTER, JR., Examiner. 

1. A CARTRIGE FOR GENERATING PROPELLENT GAS AT HIGH PRESSURE COMPRISING A TUBULAR CASE HAVING A GENERALLY CYLINDRICAL MOUTH AT ONE END OF ITS LENGTH AND A CLOSED END WALL AT THE OPPOSITE END, SAID END WALL HAVING A THICKNESS SUCH THAT RUPTURE OCCURS AT A PREDETERMINED PRESSURE TO PROVIDE A PROPELLENT GAS DISPENSING OPENING IN SAID CASE, A CHARGE OF PROPELLANT ADAPTED FOR PERCUSSIVE ADIABATIC COMPRESSION IGNITION DISPOSED IN SAID CASE, A PISTON COMPLETELY RECEIVED SNUGLY WITHIN SAID CASE ADJACENT THE MOUTH, A SUPERPOSED LAYER OF PLASTIC RESIN IN SEALING AND ADHESIVE RELATIONSHIP WITH SAID PISTON AND CASE WITHIN THE MOUTH TO DEFINE WITH SAID CASE A COMPRESSION CAVITY CONTAINING SAID CHARGE, SAID PISTON BEING FRICTIONALLY RETAINED BY SAID CASE AND ADHESIVELY RETAINED BY SAID LAYER AGAINST MOVEMENT OUT OF SAID CASE TO THEREBY SEAL SAID CHARGE UNDER SUBSTANTIALLY ATMOSPHERIC PRESSURE, SAID PISTON HAVING AN INNER CONCAVE SURFACE TO FORM A GAS SEALING SKIRT IN SAID CAVITY AND AN OUTER SURFACE PROTECTIVELY EXPOSED IN SAID CASE UNDER SAID LAYER OPERATIVE TO RECEIVE A BLOW THROUGH SAID LAYER TO COMPRESS SAID LAYER AND DRIVE SAID LAYER AND PISTON INWARDLY AGAINST SAID CHARGE WHEREBY SAID CHARGE IS COMPRESSED ABOVE ATMOSPHERIC PRESSURE UNTIL SAID PROPELLANT IS IGNITED ADIABATICALLY AND SAID END WALL SUBSEQUENTLY RUPTURED AT SAID HIGH PRESSURE. 